Tidy formatting of Reqwest errors (#4336)

## Issue Addressed

NA

## Proposed Changes

Implements the `PrettyReqwestError` to wrap a `reqwest::Error` and give nicer `Debug` formatting. It also wraps the `Url` component in a `SensitiveUrl` to avoid leaking sensitive info in logs.

### Before

```
Reqwest(reqwest::Error { kind: Request, url: Url { scheme: "http", cannot_be_a_base: false, username: "", password: None, host: Some(Domain("localhost")), port: Some(9999), path: "/eth/v1/node/version", query: None, fragment: None }, source: hyper::Error(Connect, ConnectError("tcp connect error", Os { code: 61, kind: ConnectionRefused, message: "Connection refused" })) })
```

### After

```
HttpClient(url: http://localhost:9999/, kind: request, detail: error trying to connect: tcp connect error: Connection refused (os error 61))
```

## Additional Info

I've also renamed the `Reqwest` error enum variants to `HttpClient`, to give people a better chance at knowing what's going on. Reqwest is pretty odd and looks like a typo.

I've implemented it in the `eth2` and `execution_layer` crates. This should affect most logs in the VC and EE-related ones in the BN.

I think the last crate that could benefit from the is the `beacon_node/eth1` crate. I haven't updated it in this PR since its error type is not so amenable to it (everything goes into a `String`). I don't have a whole lot of time to jig around with that at the moment and I feel that this PR as it stands is a significant enough improvement to merge on its own. Leaving it as-is is fine for the time being and we can always come back for it later (or implement in-protocol deposits!).

common/eth2/src/lighthouse.rs

@@ -364,12 +364,12 @@ pub struct DatabaseInfo {
 impl BeaconNodeHttpClient {
     /// Perform a HTTP GET request, returning `None` on a 404 error.
     async fn get_bytes_opt<U: IntoUrl>(&self, url: U) -> Result<Option<Vec<u8>>, Error> {
-        let response = self.client.get(url).send().await.map_err(Error::Reqwest)?;
+        let response = self.client.get(url).send().await.map_err(Error::from)?;
         match ok_or_error(response).await {
             Ok(resp) => Ok(Some(
                 resp.bytes()
                     .await
-                    .map_err(Error::Reqwest)?
+                    .map_err(Error::from)?
                     .into_iter()
                     .collect::<Vec<_>>(),
             )),